CHANCES OF OXFORD KNEE REPLACEMENT WITH NORMAL BMI- APPLYING ASIAN CRITERIA.

Presenting Author - SANJEEV GOKHALE
Introduction: the aim of this study was to see the prevalence of Oxford unicompartmental knee replacement surgeries in patients with normal BMI as compared to obese patients. Obesity is often measured by BMI. WHO defines normal as 18.5 to 25, overweight as 25 to 30 and obese as more than 30. Epidemiologic studies and consensus group report have shown that risk is shifted to lower BMI values in Asians. The diagnostic cut-off for overweight BMI in India is 23 kg/m2 and 25 kg/m2 for obesity (Mishra and Chowbey). Keywords: arthritis, partial knee replacement, oxford replacement. Material: two hundred OUKAs (Oxford unicompartmental knee arthroplasties) were performed for AMOA (anteromedial osteoarthritis) of the knee joints in 129 patients. Bilateral: unilateral 71: 58. Divided in two groups with two different cut-offs for obesity. First according to WHO (G1) and second for Indian population. (G2). In each there were two cohorts. In G1, First, BMI of less than 25 and the second, BMI of more than 30. In G2 the first cohort, BMI of less than 23 and the second, BMI above 25. METHODS: They were followed for three years and evaluated objectively and subjectively. Results: in G1, in non-obese patients the average improvement of OKS was 15.78. The Tegner, average improvement of 2 levels. The HKA showed average reduction of 4.94 degrees. In the obese cohort, the OKS showed average improvement of 17.56, HKA 6.04 degrees. In G2 group, non obese patients OKS changed 15.64,Tegner 2. In the obese patients OKS changed 14.56, Tegner 1.85. There was more correction of varus, more improvement of Oxford knee score, and Tegner activity level index in obese than in non-obese individuals IN G1. Non-obese in G1 had ‘better’ end OKS and Tegner but ‘less’ change. In contrast, the non obese patients in G2 achieved not only ‘better’ final OKS and Tegner they also had ‘more’ change than obese. Conclusions: with WHO criteria there was smaller difference in the number of patients between different groups (normal BMI 23 patients; obese 46 patients). But when the Asian criteria were used the difference was striking. (Normal BMI 6 patients; obese 100 patients). This suggests that the Asian criteria have a high predictive value for knowing if a patient is going to need Oxford replacement. As a side conclusion Oxford works equally well in obese patients.